Cataract Surgery and The Retina: Keeping Out of Trouble

Retinal issues can be the undoing of the perfect cataract operation making it worth revisiting how we consider and manage retinal pathologies as part of our anterior segment surgery and certainly nurture our relationships with our vitreoretinal colleagues.

The common pre-operative issues we will consider can be categorised as:

• Epiretinal membranes (ERM)
• Age-related macular degeneration (AMD)
• Diabetic retinopathy (DR)
• High myopia
• Prior vitrectomy/ oil
• Floaters
• Asteroid hyalosis

 

EPIRETINAL MEMBRANES

ERM are a common asymptomatic finding in patients presenting for cataract surgery – seen on clinical examination or with routine OCT. When the ERM is significant with macular distortion, metamorphopsia, or even a partial thickness hole, it is best to have a formal vitreoretinal assessment. Surgically, there is no significance to an ERM, but it can have a significant impact on the visual recovery and outcome. Cystoid macular odema (CMO) is more likely in the presence of an ERM.

Vitrectomy with ERM peel surgery is indicated if there is metamorphopsia or ectopic inner foveal layers with macular distortion as seen on OCT. Full thickness macula hole requires vitrectomy and membrane peel, which may be planned as a separate procedure prior to cataract surgery (Figure 1),

Lens choice is impacted by the presence of an ERM. When there is a chance of vitreoretinal surgery with gas in the eye, hydrophilic lens materials must be avoided due to the risk of lens opacification. Complex multifocal lens designs are contraindicated when there may be distorted macular function.

Intraocular lens (IOL) choice is also determined a little by the preferences of our retinal colleagues. Multifocal IOLs should not interfere with future vitreoretinal surgery but the small aperture IOL (IC8) is more challenging, and the threat is that they will just pull the lens out if macular surgery is needed (Figure 2)!

AGE-RELATED MACULAR DEGENERATION

AMD is a common associated pathology in patients with cataract. There has been ongoing controversy around the possible accelerated progression of AMD with cataract surgery and the choice of lens. The questions to be addressed are:

1. Does cataract surgery cause progression of AMD?
2. When should AMD be treated before undertaking cataract surgery?
3. Should multifocal lenses be used in patients with reduced macular function due to AMD?

The impact of cataract surgery on AMD has been disputed for decades with previous evidence suggesting a relationship between progression of AMD and cataract surgery.¹

Causation has never been demonstrated, however, and a recent meta-analysis looking specifically at this relationship concludes that although cataract surgery may be associated with progression of AMD, no firm conclusion can be made as to cause and effect.

Interestingly, they did show clearly that in Asian eyes there is an increased risk of developing AMD after cataract surgery with a risk ratio of 2–3 times non-operative patients.2

Judicious use of anti-VEGF injections for neovascular AMD prior to cataract surgery is associated with better visual outcomes.³ Concerns exist about the optimal timing of cataract surgery in individuals with neovascular AMD, as well as the amount of exudative control required before surgery for optimal results.

DR progression has been linked to cataract surgery, but it is currently held that this progression may represent natural progression of disease

Multifocal IOLs and AMD

The evidence is unclear. Theoretically the reduced contrast measurable with any presbyopia correcting lens should be a problem with AMD. Any presbyopia-correcting lens has, intrinsic in its optical design, the splitting of light so that as little as 50% may be allocated to the distance focal point and just 30% for near vision. There is also loss of light with diffractive lens designs so that up to 15% of light will be lost in the optical system.

Grzybowski et al. published a literature review in 2020 concluding that there was no evidence that patients with retinal disease should be advised against multifocal IOLs.⁴ A multifocal simulator study showed that the benefit gained for unaided near vision may outweigh the reduced contrast found with multifocal IOLs.⁵

The conservative approach is to use a monofocal lens in the presence of any maculopathy, but this denies many patients the functionality of presbyopia correction. A measured approach is to balance the complexity of the optical lens design against the likely severity of AMD. A diffractive trifocal lens is most likely to present problems in the presence of active macular disturbance. A refractive extended depth of field lens will be more forgiving. For all patients a balanced decision needs to be made between optimising visual quality and the functionality of presbyopia correction.

DIABETIC RETINOPATHY

DR progression has been linked to cataract surgery, but it is currently held that this progression may represent natural progression of disease. Maculopathy and retinopathy must be treated prior to cataract surgery. CMO is more likely after surgery in patients with diabetic retinopathy with severity proportionate to the severity of diabetic retinopathy and requires active prophylactic treatment with steroid and nonsteroidal anti-inflammatory drugs (NSAIDs). Pre-existing diabetic macular oedema will often worsen after cataract surgery and is ideally managed prior to surgery with anti-VEGF and laser photocoagulation. The management of DMO is the same as for pseudophakic CMO with the addition of anti-VEGF agents as needed. Intraoperative intravitreal anti-VEGF has been shown to mitigate the risk of DMO progression in diabetic patients.

Take care: Repeated intravitreal injections increase the risk of posterior capsule breaks and zonular weakness during cataract surgery.⁶

HIGH MYOPIA

High myopia introduces an increased risk of retinal pathology with cataract surgery. Pre-existing retinal pathology such a myopic maculopathy, lacquer cracks, or staphyloma may limit the post-surgery vision and present risks that can be reduced with preoperative  intervention. The treatment of asymptomatic retinal breaks and lattice degeneration with barrier laser is often recommended, although the role of treating these asymptomatic lesions in preventing future retinal detachment is unclear. As of 2014 there was no published evidence to support the role of prophylactic laser treatment of asymptomatic retinal breaks and lattice in preventing retinal detachment.⁷ In practice, asymptomatic retinal breaks and lattice are treated prior to cataract surgery.

SILICONE OIL

Eyes with silicone oil from prior retinal detachment surgery can be challenging cataract cases. Ideally, silicone oil is removed prior to cataract surgery. Oil droplets can be present in the anterior chamber and can appear as emulsate. Capsulorhexis will feel different (as in any vitrectomised eye) as there is no vitreous face to support the capsule. Silicone oil will adhere to the surface of certain IOLs causing visual disturbance. Silicone lenses were particularly bad with up to 80% of the lens surface being irregularly covered in silicone oil causing significant visual disturbances. Hydrophilic materials exhibit the least oil affinity but are contraindicated when intraocular gas may be used. Modern hydrophobic lenses exhibit some but tolerable oil affinity.⁸

The vitrectomised eye has less support of the lens and capsule and it may be useful during surgery to reduce the infusion pressure during phaco with a corresponding reduction in aspiration rate to minimise the overdeepening of the anterior chamber.

FLOATERS

Floaters are common, occurring in up to 76% of the community with 33% of subjects reporting visual impairment due to them.⁹ Patients having cataract surgery will often experience a worsening of floater symptoms, blaming this on the operation and resulting in dissatisfaction. Surgically induced posterior vitreous detachment (PVD) may cause the onset of new floater symptoms as can vitreous hydration during high pressure phaco with altered Troxler effect. More commonly however, patients will become more aware of pre-existing floaters through better vision and increased vigilance.

Transient floaters of new onset after cataract surgery may represent fine lens particles entering the anterior vitreous during surgery. It is hypothesised that this occurs when the anterior hyaloid membrane is disrupted as can happen with over pressurising the eye during hydro dissection. These tend to disappear over one month.¹⁰

CMO is more common in patients with diabetic maculopathy, epiretinal membrane, prior macular surgery and underlying uveitis

Floaters are most commonly treated with YAG laser vitreolysis or pars plana vitrectomy (PPV). In patients with cataract where floaters are significantly troubling, combined cataract and PPV may be the intervention of choice. Cataract is a common complication of PPV surgery for floaters with a reported incidence of almost 50% occurring at a median 16 months after surgery.¹¹

ASTEROID HYALOSIS

Asteroid hyalosis is a benign accumulation of calcium pyrophosphate spheres within the vitreous body that usually causes minimal disturbance of vision. In most cases asteroid hyalosis has no impact on cataract surgery. If the asteroid particles are significant, care must be taken to avoid falsely short readings of axial length if ultrasound biometry is used (for dense cataract). While there is scant literature, it would seem wise to avoid hydrophilic IOLs with the increased calcium content of the vitreous. Lens surface calcification is described on silicone IOLs when implanted in patients with asteroid hyalosis.¹²

Rarely asteroid hyalosis can cause reduced vision after cataract surgery – particularly if multifocal IOLs are used. This is more likely if a PVD occurs during surgery and there is a compaction of the calcific particles in the anterior vitreous.¹³ Pars plana vitrectomy offers a solution in these cases (Figure 4).

INTRAOPERATIVE CONCERNS

Intraoperative issues during cataract surgery can include:

• Posterior capsule fracture (PC#), vitrectomy
• Dropped lens

Posterior Capsule Tear

The most common intraoperative retinal problem the cataract surgeon will face is a torn posterior capsule (PC). The published incidence of PC tear varies between 0.45 and 3.6%. It is worth noting that the incidence of PC tear is more than doubled in patients who have had intravitreal injections. Considerations with a torn PC are:

1. Managing the vitreous that may prolapse into the anterior chamber and out of the wounds,
2. Controlling the lens, nucleus and fragments that may fall through the PC# tear into the posterior segment,
3. Placement of an intraocular lens.

Measures should be taken to minimise vitreous prolapse. Maintain a pressurised and formed anterior chamber (AC) and use viscoelastic to tamponade vitreous at the plane of the torn PC. Despite these measures vitreous will often prolapse and vitrectomy is required. Vitrectomy can be approached via the anterior chamber (anterior vitrectomy) or via the pars plana. It is a topic of ongoing debate as to whether a cataract surgeon should use an anterior or pars plana approach.

Anterior vitrectomy avoids the need for a new wound and the risk of seeding organisms into the vitreous but has the downside of extra vitreous being pulled into the anterior chamber. Posterior vitrectomy presents an unfamiliar procedure but has the benefit of better clearance of vitreous from the anterior chamber as vitreous is pulled posteriorly.

The most important principle when performing vitrectomy is to avoid any traction on the vitreous. The goal of anterior (or pars plana for anterior segment) is to clear vitreous from the AC and the area of lens implantation. Sounds obvious but there are several pitfalls.

• Never sweep vitreous from the wound but rather cut it with a vitrector. • Use the highest cut rate possible to avoid tugging on vitreous with each cut.
• Use irrigate/ cut/ aspirate for most of the vitrectomy so vitreous strands are not being pulled into the port.
• Separate the infusion and cutter and do not use the main phaco wound.
• Minimise hydration of the vitreous by using irrigation in front of iris and directed anterior.

Triamcinalone is useful to stain the vitreous as it is easy to miss some and find it at the wound postoperatively. Thorough vitrectomy using high speed cutting minimises the risk of retinal detachment and giant retinal tears.

Lens Fragments

Lens fragments falling into the vitreous through a rent in the capsule is less common with an incidence of up to 1% of cataract surgeries,¹⁴ although there are no recent studies to give a true incidence with modern surgical techniques. Retained lens fragments in the posterior segment can result in inflammation with CMO, increased intraocular pressure and retinal detachment and – unless very small – will require removal. During the cataract surgery, if the lens nucleus falls into the vitreous after a capsular tear, no attempt should be made to retrieve it from the anterior segment. The risk of tractional retinal detachment and giant tear is high with uncontrolled fishing in the vitreous. Perform a thorough AC vitrectomy (ideally via the pars plana) using triamcinalone and ensure there is no vitreous to wounds. Place a lens in the sulcus with optic capture if there is adequate capsular support (though there is contrary evidence suggesting that patients do better if a lens is not inserted at the time of complicated phaco surgery)¹⁵ and suture the wounds.

Seek out your vitreoretinal colleague to plan PPV with lens removal. The optimal time for PPV and lens removal from the vitreous is at the time of the original cataract surgery but this will be limited by the availability of the vitreoretinal surgeon.

It is important to identify CMO risk factors prior to surgery

POST-OPERATIVE CONCERNS

As cataract surgeons, some of the postoperative issues we see include:

• CMO,
• Retinal detachment,
• Poor quality of vision; floaters, macula path, ERM, rare macula pathologies.

CMO remains a common cause of reduced vision after cataract surgery despite modern surgical techniques with an incidence of between 0.1 and 3.8% (though angiographically the incidence is as high as 30%) with peak onset at five weeks post-op.¹⁶

CMO is more common in patients with diabetic maculopathy, epiretinal membrane, prior macular surgery and underlying uveitis but also occurs in routine surgery with no identifiable risk factors. Surgical events such as extra iris manipulation (as in cases with small pupil or synechia) and PC rupture, particularly with vitreous prolapse to the anterior chamber, also increases the risk of CMO. It is important to identify CMO risk factors prior to surgery (ERM, diabetic maculopathy, prior macula surgery) so that patients can understand that CMO is more likely with their surgery, and it is not caused by the cataract surgery alone.

Prophylaxis against CMO is the current standard of care, using a combination of topical steroids and NSAIDs, as this has been demonstrated to be more effective for preventing CMO than either drop alone.¹⁷

Treatment requires identification of any underlying risk factors such as retained lens fragment, vitreous in the anterior segment or ERM and the use of topical steroids plus NSAIDs (Figure 5). If there is inadequate response after four weeks of topical treatments sub-Tenons Kenalog or intravitreal triamcinolone may be considered. The problem with intravitreal steroid is that this may necessitate repeated injections as it is a relatively short acting treatment.

Significant CMO that is unresponsive to treatment in the absence of inflammation elsewhere in the eye may be a situation where a short course of intravitreal anti- VEGF will resolve the problem.

When CMO is not responding to treatment it is time to look deeper. Is there  inflammation in the other eye also? This may represent an underlying, undiagnosed uveitis (such as sarcoid) that will require different and possibly systemic antiinflammatory treatment.

Diabetics require extra vigilance for postcataract macular oedema and the use of prophylactic NSAIDs and anti VEGF treatment has been shown to significantly reduce the incidence.¹⁸

Unexplained Poor Vision

Unexplained poor vision after cataract surgery can be a difficult conversation. We exclude the obvious things:

• Capsule opacification,
• Lens optical design – often enough, patients experience general poor-quality vision with some current lens designs where vision will have been bad from the day after surgery,
• Corneal aberrations – look for form fruste keratoconus or significant coma,
• Ocular surface disease with significant dry eye – fluctuating vision, and
• Lens alignment with the visual axis – for any presbyopia lens design.

And then we look to the retina for answers.

CMO will be the most common cause as discussed above. An ERM that has progressed can cause specific metamorphopsia symptoms or less welldefined changes in visual quality. ERM can drag the macula, resulting in symptoms ranging from shadowy vision to full diplopia. Retinal misregistration is common in patients with ERM and does not always result in diplopia. ERM surgery is effective for alleviating diplopia caused by ERM.¹⁹

Paracentric Acute Middle Maculopathy

Paracentric acute middle maculopathy (PAMM) is a less well-known condition that may account for those cases where we just cannot find a reason for poor vision. Macular ischaemia causes symptoms of a paracentral scotoma, possibly with diminution of vision. Symptoms can be as vague as general blurring of central vision. Diagnosis is made on characteristic OCT-A and SD-OCT findings. While there is no treatment, vision often improves spontaneously over several months (Figure 6).²⁰

ACHIEVING EXCELLENT VISION

Retinal problems need not detract from the possibility of excellent vision for our patients. It is better to identify, discuss and treat pre-existing conditions. Choose the IOL appropriately. Capsule rupture and a nucleus falling into the vitreous will happen and we need to have a pre-considered plan for how to deal with the situation.

Patients being counselled for cataract and lens implant surgery need to know that while we may be planning for spectacle-free emmetropia with a trifocal toric IOL there is always a chance that this will not be possible. The trickiest situation is when everything looks perfect, but vision is poor; then we look to the less common retinal conditions like PAMM that are so hard for the cataract surgeon to diagnose.

So, send your vitreoretinal surgeon a Christmas card every year – it’s worth investing in the relationship!

Retinal problems need not detract from the possibility of excellent vision for our patients. It is better to identify, discuss and treat pre-existing conditions. Choose the intraocular lens appropriately

 

Dr Patrick Versace MBBS FRANZCO has over 30 years’ experience in ophthalmology. Based in Sydney, he is a leader in ophthalmic surgery, specialising in cataract and refractive procedures. He holds appointments as a senior lecturer in Optometry and medicine at The University of NSW and staff specialist ophthalmologist at The Prince of Wales Hospital Randwick and Sydney Eye Hospital providing clinical service and registrar surgical training.

After gaining Anaesthetic qualifications in London Dr Versace completed his specialist ophthalmology training with Sydney Eye Hospital to become a Fellow of the Royal Australian and New Zealand College of Ophthalmologists. Dr Versace has been involved in numerous clinical trials and is often an invited speaker at international meetings.

 

Dr Chris Qureshi BSc(Med) MBBS MMed(OphthSc) FRANZCO is a specialist vitreoretinal surgeon with over 13 years’ experience in the field of ophthalmology. He graduated with a double degree in Medical Science and Medicine and Surgery from the University of NSW and went on to complete a Masters in Medicine in Ophthalmic Science at the University of Sydney.

Dr Qureshi has completed two vitreoretinal fellowships at Westmead Hospital, Sydney and at Oxford University and Oxford Eye Hospital in the UK.

He is a senior staff specialist at Westmead Hospital and participates in research and training of registrars, residents, optometrists, and medical and optometry students. His special interests include treatment of the retina and macula such as retinal detachment, macula hole, epiretinal membrane, age-related macular degeneration, diabetic retinopathy, retinal vein occlusion and vitreous floaters.

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